Complex anomalous Hall effect in ferrimagnetic CoxGd100−x (39 ≤ x ≤ 73) alloys

Rare-earth and transition-metal (RE-TM) alloys have been studied extensively due to their unique optical and magneto-transport properties for advanced magnetic memory devices. Recent studies reveal an extra hump in the anomalous Hall effect in ferrimagnetic CoxGd100−x alloys with x ≈ 78, yet its origin is still ambiguous. In this article, the magnetic properties and Hall effect have been studied in CoxGd100−x alloys with varying Co concentrations in the range of 39 ≤ x ≤ 73. Complex anomalous Hall effect, including temperature-dependent polarity reversal and the appearance of an extra hump, has been found in a certain range of Co concentration. These characteristics were explained by the combined effect of magnetic domain evolution and spin-flop behavior. These results are helpful for understanding the complex transport properties in the RE-TM ferrimagnetic alloys.